The present invention relates generally to telecommunications, and more specifically to a method and system of providing telecommunication services that is flexible and efficient. Existing Public Switched Telephone Network systems suffer from a number of problems including system complexity, access being proprietary and services being implemented on fixed hardware. As a result, new services are complex and costly to develop, so telcos only provide services that appeal very broadly. The invention provides an open and flexible system by describing communiations in terms of graph packets which contain pointers to blocks of software code, rather than containing large blockes of executable code. In the preferred embodiment, these graphs identify software filters which are dedicated to particular tasks, and are based on a standard API. This allows third parties to create new filters and make them available, allowing new services to be provided quickly and easily.